1. Field of the Invention
This invention relates to a communications terminal particularly suited to ensuring man-machine communications notably, but not exclusively inside the cockpit of an aircraft.
2. Description of the Prior Art
In this context, the utilisation of terminals comprising a viewing screen integrated into a command device is known.
This command device comes either in the form of a keyboard fitted with keys integrated into the terminal, or in the form of a transparent touch-sensitive surface disposed against the screen.
In the form of a keyboard, the command device has the inconvenience of obliging the operator to continually displace his field of vision between the screen and the keyboard. In addition, this type of control means does not easily enable the designation of an area of the screen or the displacement of an object displayed on the screen.
In the form of a transparent touch-sensitive surface, the command device enables the inconveniences of the keyboard to be suppressed but is unusable with screens of small dimensions especially in the context of the cockpit of an aircraft. Indeed, when the operator puts his finger on this surface, e.g. to activate a command, he masks a large part of the screen with his hand.
Moreover, the applying of fingers on this surface inevitably leaves traces which, over time, affect the visibility of the screen.
Furthermore, a touch-sensitive surface on a screen does not enable the feeding back to the user of the confirmation of his action by mechanical perception of stress break.
For these reasons, the utilisation of a transparent touch-sensitive surface placed in front of the screen is difficult to envisage in the context of aviation where security instructions are very restricting.
Furthermore, modern aeronautical applications require the use of an increasingly bigger viewing screen, the dimensions of this surface being limited by the space available in a cockpit.